Cloud computing is a user environment where users receive services through networks such as the Internet, and the spread of cloud computing has been promoted in recent years. In cloud computing, many tenants (users) use servers installed in a large data center or the like. This method causes an advantage of scale, and a unit price for use of an infrastructure of the data center may be reduced. Since the tenants may outsource operations and management of the servers to a provider (service provider) that provides services, a cost of the operations and management may be reduced.
FIGS. 1A and 1B are diagrams illustrating examples of the type of a multi-tenant architecture that achieves cloud computing. FIG. 1A illustrates a multi-tenant architecture called an Infrastructure-as-a-Service-based (IaaS-based) virtual native Platform as a Service (PaaS). As illustrated in FIG. 1A, the virtual native PaaS has a layer structure composed of constituent elements such as hardware, virtual machines, operating systems (OSs), databases (DBs), and application software (hereinafter referred to as applications). In the virtual native PaaS, only a hardware infrastructure is shared by tenants. A virtual machine, an OS, a DB, and an application are used for each of the tenants. In the virtual native PaaS, each tenant may freely select and combine a virtual machine, an OS, a DB, and an application.
FIG. 1B illustrates a multi-tenant architecture called a multi-tenant native PaaS. As illustrated in FIG. 1B, the architecture that is called the multi-tenant native PaaS has a layer structure composed of constituent elements such as hardware, an OS, a DB, an application, and the like. In the multi-tenant native PaaS, not only the hardware but also the OS, the DB, and the application are shared by tenants. Only business processes that are executed by this infrastructure are different for the tenants. In the multi-tenant native PaaS, the application and the DB are shared by the tenants. Thus, an aggregation efficiency of the infrastructure is high and efficiencies of operations and management may be improved. As related art, there are Japanese Laid-open Patent Publication Nos. 2010-140209, 2011-154540, 10-134066, 11-53191, Junichi Niino, “Course of Evolution of PaaS and Cloud Platform without Virtualization”, online, searched on Mar. 7, 2012, <URL: http://www.publickey1.jp/blog/11/paas_1.html>, and the like.
In the virtual native PaaS, the virtual machines, the OSs, the DBs, and the applications are different for the tenants, and processes are separately executed for the tenants in an actual operation. Thus, the architecture is redundant and is not efficient, and servers of a data center may not be effectively used in the virtual native PaaS. In addition, a provider of the virtual native PaaS manages combinations of a large number of constituent elements. Thus, operations and management of the servers are complex, and an operation cost (running cost) per tenant is high.
In the multi-tenant native PaaS, the OS, the DB, and middleware are shared by multiple tenants, as described above. Thus, each tenant does not freely select an OS, a DB, and the type of an application, and the flexibility of selecting an architecture is low.